Electrical semipotentiometer



Feb, l0, 1931. s. c. HORN 197919563 ELECTRICAL SEMIPOTENTIOMETE FiledNov. 17, 1928 ,QQMNW AITTORNEY Patented Feb. lO, lllll NETE@ STATES@a-TENT @FFHQ SIDNEY C. HORN, OlF MOUNT VERNON, NEW YORK, ASSIGNOR TOWILSON-MAEULEN COMPANY, INC., OF NEW YORK, N. Y., A. CORPORATION OF NEW,YORK ELECTRICAL SEWIPOTENTIOMETER Application led November 17, 1928.Serial No. 320,1?4.v

rlhe present invention relates to electrical measuring instruments andhas particular reference toan indicating type of potentiometer,especially to those potentiometer indicaters employing thermocouples andWhich may be used for measuring temperature, although it is not limitedto use for temperature measurements only.

As is Well known, in prior null method, potentiometric measuringinstruments, the deiecting galvanometer and its associated deectionscale are distinct from, and usually separately mounted away from theadjustable slide Wire and its integrant, calibrated, measuring scale.

ln instruments of the above character, it is manifest that the observercan only obtain readings by manual adjustment of the slide Wire, and beguided in such adjustment by optical observation of the galvanometerpointer and the zero markings on its associated scale. I

This operation of observing the galvanometer, While adjusting the slideWire, elsewhere, until the galvanometer shows no deiection, and thentransferring visual observation to the calibrated slide Wire dial, tonote the reading or measurement, is inconvenient, especially When thegalvanometer deflection scale is uncalibrated, as is usually the case.Readings, under such circumstances, can only be taken from the slideWire calibrated scale, and then only When-the slide Wire has been so'adjusted as to bring the galvanometer to zero (balance) or index of nodeflection on its scale. Again, since the galvanometer ydeflection isuncalibrated, except as to' the fixed index of no deflection, the amountof error cannot be observed.

Now, instruments known as semi-potentiometers or dellectionpotentiometers employ a calibrated galvanometer scale. rlhat is to say,both the galvanometer andslide Wire scales are calibrated. Also, it iscustomary, and to a considerable extent necessary, to have an additionalcompensating slide Wire to compensate for changes in resistance of thegalvanometer circuit. Thus, approximately exact readings can :be takenWithout adjusting the slide -wire and Without bringing the galvanometerto zero, or point of no deflection. ln this case,ihow ever, theoperation involves the observation of both scales and involves acalculation, as Well. A reading must iirst be taken from the calibratedslide Wire scale, at its index point, then a reading must be taken fromthe galvanometer deflection scale, and the latter reading added to ordeducted from the reading on the slide Wire scale.-

When measuring only electrical voltage, such a customary type ofsemi-potentiometer, may have no greater disadvantages than those statedabove. But when the voltage is being measured as the indirect means of'measuring some other physical properties,

such as temperature, there is still another objection.

rlhis latter objection is due to the fact that the voltage and thevariable being indirectly measured may not have proportional values.

lF or example, the above objection occurs in the case of aplatinum-rhodium thermocouple, in measuring temperatures in pyrometry,Where the relation between degrees of temperature and voltage deliveredby the thermocouple is approximately a parabolic relation. Such aninstrument calibrated therefore in degrees of temperature, in accordanceWith the thermo-electric characteristics of a platinum-rhodium couple,Would have unequal scale divisions on the slide Wire scale, and anyscaledivisions determined upon for the galvanometer scale Would only beappropriate for one setting of brush on the slide Wire.

ll have therefore designed and re-arranged the above types ofinstruments as to eliminate the objections noted, and to permit,substantially, of a joint reading. In my improved instrument there ismade possible the use of a single, dual purpose, calibrated scale. forcombined and instant slide Wire calibration and galvanometer calibrationand reading. At the same time the novel design permits this single scaleto have calibrations either in terms of voltage or of the valuesindirectly measured through measuring voltage.

For example, when my improved instruin a directonthat willtend-toproperly'add ated- .y gsaid galvanometerland having 'a 5' slide Wire,and for deflections of u n co thermo-electric characteristics of the cLiibrated.

fet such calibrations would be both for adjustments of brush on accurateprimary the galvanometer. Thus, it is possible by my novel design tomalte adjustments of the brush on the primary slide Wire to followroughly' 'the voltage being measured, and permit the final reading to betaken from the same identical scale according to the pointer of thegalvanometer as indexed, irregardless of the position the brush occupieson the primary slide Wire. f

The present invention, then, permits/the observer either` to bring thegalvanometer readings to a permanent Zero point, and take the finalreadings from the slide Wire index on the single scale which would givea reading by the customary null method of potentiometers, in general;or, the observer can ,simply alter the relation of primary slide Wireand brush to bring the' galvanometer pointer into the field of visionand take the reading on the single scale.,` from the galvanometerpointer, as indexed. n

Accordingly, one of the main objects of my present invention is toprovide an electrical measuring instrumdnt of the semipotentiometer typein which the two customarily separate slide Wire and galvanometer scalesare combined into a single Scale, therebyfto facilitate a reading ofmomentary value indicated on the scale, when the latter is under directobservation. y

Another important object of this invention is to "provide apotentiometric electrical measuring instrument in Which a reading can betaken directly from the scale at the position of the galvanometerpointer, regardless of whether or not the slide Wire'is exactly adjustedto bring the gnlvanometer to Zero, or point of no deflection. v

Another object of the invention is to provide an indicatingpotentiometer'in which the scale of a deilecting galvanometer is madeidentical with the calibrated adjustable slide "Wire scale, so that thecalibrated slide Wire scale also acts With suiiicient precision inpractice as a calibrated deflection scale for thegalvanometer, andsothat the slide Wire scale fixed.l index coincides with the zero, or point of no deflection of the galvanometer:

Another object of the invention is to provide a potentiometer in whichthe galvanometer issoconnected as to electrical polarity,

that when the calibrated'rslide wire isout.

'of' adjustment, the ,galvanometer ,will ,deflect on the calibrated.scale from the fixed index,

rnocouple for which the instrument is.

or subtract the equivalent value ci the slide Wire misadjustrnent, whenthe reading is talren from the position of the galvanometer pointer onthe scale instead of from the hired index.

Another object of the invention is to provide a poteniometric instrumentin which the operator, or user, may adjust the slide ivire and itsintegrant scale until the galvanometer stands at no defiection and thegalvanometer pointer coincides with the fixed inden, thus giving anenact reading at that point, and thereafter the operator or user mayobserve and read direct from the scale at the position of thegalvanometer pointer, actual temperatures, even when there are minorvariations of the electrical values be- A ing measured, vvlthout furtherslide Wire adjustment.

Another object of the invention is to pro vide a novel instrument of thecompensating slide wire, deflection potentiometer type, in which asingle calibrated scale serves for both slide Wire and galvanometerscales, and moves as a unit, either with the primary slide Wire or thebrush for the slide Wire, and the scale, being movable with respect tothe gal vanometer pointer, such as the index, is mounted as a circularband, to be rotated, or as a strip scaleto be moved back and forthlongitudinally.

And other objects ofthe invention are to improve generally 'thesimplicity and efficiency of such devices and to provide a device orapparatus of this kind which is economical, durable and reliable inoperation, and

economical to manufacture.

The inventive features for the accomplishment of these and other objectsare shown herein, in one preferred embodiment, in connection with animproved potentiometer which, briefly stated, includes a verticalrotatable shaft and support therefor, a circular index support mountedthereon for movement with said shaft, an indexlscale mounted on saidindex. support, said scale having indic'ia thereon representingpredetermined divisions or units and values of the physical propertybeing measured, an electrical reslstance associated with said scale andadapted to function as a primary slide` Wire resistance, a slideassociated with said resistance, a second resistance means mounted onsaid shaft and adaptedtofunction as the. galvanometer compensation slidewire resistance, a gear on said shaft operatively .associated with apinion gear adapted to be manually actuated to simultaneously move thescale and the first and second resistances` as a single unit, a slideassociated with said resistance, a moving .galvanometer coil sus-.pended over said first 4resistance and elecportion adapted to travelover the surface of said scale, and a fixed zero index means for thescale so arranged so as to coincide with vimproved potentiometer andgalvanometer means, removed from the housing, with associate indexes andappui-tenant parts, and havingl the electric circuits disclosedthereabout, dagranmiatically, for clearness in showing.

ln the accompanying drawings, like characters of reference indicate thesaine parts in the different views. The device comprises a circular,potentiometer slide wire carrying index sleeve, denoted by 8, which isaxed to a rotatably mounted vertical shaft 2, the latter beingsupported, for rotation, in alined bearings 5 and 6, said bearingsoutstanding horizontally from a wall plate 1, which is provided with aplurality of holes a, to permit of attaching to the housing and a wall,by screws, not shown.

The dielectric index carrying `sleeve dial 8 is relatively fixed to theupper end of shaft 2, Fig. 2, and rotates therewith, the boss 8 thereofresting upon the top face of the upper bearing lug 6.

rllhe lower end of the shaft 2 has fixedly attached thereto a shaftdriving gear 3, the lower face of which rests upon'top face of lowerbearing lug 5, the shaft 2 extending therethrough and mounting an endcollar 2 thereon, to hold shaft against endwise movement.

rlhe lower bearing 5 has an odset auxiliary bearing 5 into which isrotatably mounted a pinion shaft 13, with a pinion 4 fixed thereto onthe upper fact of bearing 5. and a knurled adjusting knob 14 fixed tothe lower end thereof against the lower face of bearing 5. rllhe pinion4 meshes with gear 3 and rotation ofthe knob 14 causes shaft 2 to rotateand with it the above described assembly and, also, the following notedstructure.

rll`he shaft 2 also has ixedly carried thereon for rotation thereby adielectric annulus 'l' which mounts in a suitable manner upon thegrooved periphery thereof, a galvanometer compensation resistance means23, the func'- k tion of which will be later described. rlhe foregoingshaft mounted structures and moving means constitute the manlpulativecontrol for the instrument. The dial sleeve 8 has mounted near its uppered ey acircumferential index scale 17 which 1s calibrated EN ai as at19, with indicia, to indicate desired units or values of such physicalproperties, such as temperature, as are 'being measured.

rilhe dial sleeve 8 also mounts, below the index scale 17, an electricalresista-nce 20, which is mounted and secured to the face of sleeve 8similar to the manner of mounting resistance 23 to annulus 7. Thefunction of this resistance is to act as a primary or potentiometercircuit control means, the detail of which will be later described.

Mounted upon the wall bracket 1 is an outstanding boss 5 upon which isattached a fixed, potentiometer resistance contact slide 9, betweenwhich and thel boss b is mounted an insulator base c.

Similarly, the galvanometer compensation resistance 23 is also served bya similar contact slide 22, mounted upon an insulated support b c. Bothslides or brushes 9 and 23 are angular' in contour, and are oii'set,except as to their Contact ends to clear the operative diameters oftheir respective resistances.

llhe galvanometer 10, of the moving coil type, is shown in Fig. 2, indiagrammatic form and in relative operative association with theforegoing described apparatus, and as a part of the diagrammaticcircuits shown in conjunction with the instrument. Any suitable mountingof the galvanometer 10, by its bearing pivots 11--11 may be used. Thegalvanometer carrier in, and actuates, by 'one of its pivots l1, agalvanometer pointer or indicator 12, and during the oscillation of thegalvanolneter, by defiection, about its axis which coincides with theaxis of shaft 2 and the sleeve scale 8, the pointer 12 will move inassociate relation to the index 17. The tip of pointer 12 may be bent atright angles, as at 15, to enable it to be readily visible at thereading face of index 17.

lt is understood the foregoing description as to the mounting of thegalvanometer and pointer relates to the form disclosed, and that themeans of mounting the galvanometer and its pointer may be modified. ln

some forms of structure the.galvanometerV may be mounted by eithersuspension or a monopivot, as desired. 'lhe pointer may. also bemodified in its associate relation to the galvanometer by being attachedto the moving coil or the suspension means of the galvanoineter or toany means whereby the gai- A vanometer itself may be operatively mountedfor desired action.

The upper bearing 6 carries an extension lug 21 on its front face uponwhich is mounted, in a position to be prominent` but to clear the scalesleeve diameter, a fixed pointer or Zero indicator 24. the upper end ofwhich is pointed and is visibly related to the lower line of the index17. The function of this fixed zero 'point is to act as a galvanometerzero reference when the galvanometer and its mareos that readings takenin the manner stated above, When the galvanometer is deflected may beonly approximate and not exact.

This is so since the deflection of the galva* nometer for a givenvariation, from slide Wire setting, of the quantity measured will not bethe same when large quantities are measured, as When small totalquantities are measured.

However, byarrangement of design, either by length of galvanometerpointer or other- Wise, the values of the galvanometer deflecs' tion canbe made to nearly coincide with the values of the slide Wirecalibration. Thus, the measurement read When the galvanome4 ter isdeflected, will be exact enough for many purposes and uses,.besidesbeing extremely convenient and simple in use.

The invention disclosed herein is applicable to devices other thanelectrical measurement instruments or pyrometers. It is applicable toautomatic regulating and controlling and automatic signalling devicesWhich employ potentiometric electrical measuring principles, and whichutilize galvanometer deflection to initiate, through associa-tedmechanism, controlling or regulating action.

For example, the invention can be employed with a potentiometricautomatic temperature controller if used in connection With the novelgalvanometer for exploring the position of the pointer and maintainingregulation of the physical value being measured under the control of thegalvanometer defiection. The combined scale 19 operates similarly, bothfor a simple indicating instrument, as shown in Fig. l, and for acontroller type of instrument.

Tn this controller application, the operator` or supervisor can quicklyand conveniently read minor defiections from the temperature at Whichthescale 19 is set for control. This obviates the need for disturbing thesetting, as would be necessary'in prior instruments employing aseparate, uncalibrated deflection scale for the galvanometer, or theneed for making a calculation, but separated galvanometer deflectionscale.

`When thus employed, the present invention adds the advantage ofconvenient direct indication of the temperature, to the other functionsof the instrument, Without the neeessity of disturbing the slide Wiremember, this setting being also capable of functioning as the setting ofthe controlling, regulating or signalling function.

The foregoing detailed description has been given for clearness ofunderstanding. Hence, no unnecessary limitations should be understood.Further, the appended claims should be construed as broadly aspermissible in view of the prior art, since many and various changes maybe made Without departing from the scope of the invention as defined inthe broader claims.

Having thus described my invention what claim is:

l. The combination of a semi-potentiometer measuring instrumentcomprising a defiecting galvanonieter and a slide wire, with a commonreading index therefor.

2. The combination With a potentiometer, comprising a galvanometer, aprimary slide Wire, and a galvanometer compensation slide Wire, of acombined slide Wire. and galvanometer scale therefor.

3. A potentiometer comprising, with a defiection galvanometer, acircular primary slide Wire, a galvanometer compensation slide Wireconcentric therewith, and a combined circular slide Wire andgalvanometer reading scale concentric With said slide Wires.

4. A potentiometer comprising a deflecting galvanometer coil, anindicator carried thereby, circular primary and compensating slide Wireselectrically associated with said coil, means for moving said Wires, anda combined galvanometer and slide Wire reading scale concentric withsaid indicator and said Wires.

5. Anelectrical measuring instrument, employing a deflectionpotentiometer circuit in which the slide Wire is of circular form, incombination with a fixed galvanometer Whose scale is carried incombination by said circular potentiometer slide Wire, said slide Wireand scale being rotatable about the axis of said fixed galvanometer, anda fixedindex for said galvanometer scale.

6. An electrical measuringA instrument employing a deflectionpotentiometer circuit the slide Wire of which is of circular form With ascale attached thereto, in combination with a fixed galvanometer mountedcoaxially to` said slide Wire, the pointer of said galvanometer playingover said slide Wire scale and said slide Wire and scale being rotatableas a unit.

'7. Tn a measuring instrument, the combination of a balancing meanscomprising a pair of relatively movable parts one of which carries ascale and the other a pointer; said balancing means including meansassociated with the scale for approximately indicating on the scale whatpoint on the scale should register With the index to obtain a balance.

dll

bsaid sca disposable opposite said index; and ci-necb ing, whenbalancing means is unbalanced;

u to approriinately indicate what point on the scale could be brought tothe pointer to obtain a balance n 9. A derlection potentiometercomprising a pair of relatively movable supports; a slide vvire and ascale carried on one of said supports; the other support carrying anindex associated with said scale; and a galvanometer having a pointerassociated with the scale and index; said scale being a common scale toboth the slide v/ire and the pointer.

l0. deflection potentiometer comprising a pair of relatively movablesupports; a slide Wire and a scale carried on one of said supports; theother support carrying an indes associated with said scale; and agalvanometer having a pointer associated with the scale and index; saidscale being calibrated and disposed relative to the index to give directreading of the quantity to be measured when the potentiometer isbalanced; said pointer being opposite the index vvhen the potentiometeris balanced; said `member, ivhen the potentiometer is slightly unbalanced deflecting and indicating on the scale an approximate reading otthe quantity to be measured.

l1. A deflection potentiometer comprising., a slide Wire and a scalemovable together; a fixed index associated with said scale; agalvanometer having -.a pointer associated with the scale and indea;said pointer being opposite the index 'when the potentiometer isbalanced; said member when the potentiometer is unbalanced detiecting`from the index an amount substantially equal to the dilierence betweenthe amount to be measured and the amount indicated by the indes: on thescale,

l2. A detlection potentiometer comprising,

a slide wire and a scale movable together;

"a fixed index associated with said scale; a

galvanonieter having a pointer associated with the scale; said scalebeing calibrated and disposed relative lto the indes to give directreading oit the quantity to be measured when the potentiometer .isbalanced; said pointer being opposite the indeir when the potentii-ometer is balanced; said pointer, vvhen said quantity is in excess oi"balancing amount; deecting toward the higher end of the scale an amountsubstantially equal to the scaleunits indicating such eac/ess; saidpointer; when said quantity is less than balancing amount, deiectingtoward the lower end the scale an amount substantially equal thescaie-units indicating the deliciency. i3. il deflection potentiometercomprising a slide Wire and a scale oscillatory together; a lined indexassociated with said scale; a dried galvanometer having a pointerassociated With the scale and movable on an anis :having a pointerassociated With the scale and movable on an anis coincident with ltheaxis ot' relative oscillation oi' said supports; said scale beingcalibrated and disposed relative to the index to give direct reading oitthe quantity to be measured When the potentiometer is balanced; saidpointer being opposite the index when the potentiometer is balanced saidpointer, vvhen said quantity is diderent trom the balancing amount,dedecting trom the index an amount algebraically substantially equal tothe scale-units indicating the difierence; whereby the amount to be measured is substantially indicated on the scale by the pointer as anapproximate final reading or as a reading indicating the point on thescale to be brought to the index *for an accurately balanced reading.

15. A potentiometer comprising a pair of relatively movable supports; apotentiometer slide Wire; a compensating slide Wire parallel thereto anda scale carried on one ot said supports longitudinal to the direction otrelative movement; the other support carrying an index associated withsaid scale, a galvanom eter having a pointer associated with the scale;and a pair of contactors engaging said vvires respectively; a currentsource of conetant potential-and constant internal resistance having itspoles. respectively connected to the ends ot the potentiometer Wire; asource of potential variable as a function or" a quantity to bemeasured; conductors connecting said source ot potential andgalvanometer in series between one end ci the com pensating vvire andthe' opposite end of the potentiometer Wire; said scale being caliVloratedand disposed relative to the indea to give direct reading of thequantity to be measured when the potentiometer is balanced lab and nocurrent passes the galvanometer; said dedector member being opposite theindea when the potentiometer is balanced and, vvhen said quantity isdiderent from balancing amoum, deecting from he index an amountsubstantially equal to the scale units indicating such derence.

Sign/ed au, New York, in the county of Bronx and State of New York, this9th day of November, A. D. 1928.

SIDNEY C. HURN.

